Mount Marcus Baker, Mountain summit in Matanuska-Susitna Borough, United States.

Mount Marcus Baker is the highest peak in the Chugach Mountains of Alaska, located roughly 120 kilometers east of Anchorage. It rises to approximately 4,016 meters and dominates the skyline of this major mountain range.

The peak was named in honor of cartographer Marcus Baker, who contributed to early surveys of Alaska. Its original name, Mount Saint Agnes, was later replaced to recognize Baker's work in mapping the region.

The peak's Ahtna name is Ts'itonhna Dghilaaye' and its Dena'ina name is Ch'atanhtnu Dghelaya. The English name honours Marcus Baker, a cartographer and geologist; before the change the mountain was called Mount Saint Agnes, after the wife of USGS's James W. Bagley, who added "Saint" hoping the name would stick.

Climbing the peak requires technical skills with snow and ice, along with specialized equipment for safety. The best climbing season runs from April through June, when conditions are most manageable for the ascent.

Mount Marcus Baker ranks 67th in the world by topographic prominence, with a prominence of 3,269 metres, because it rises almost straight from tidewater. Its west flank holds the roughly 40-kilometre-long Knik Glacier. The peak's Ahtna name is Ts'itonhna Dghilaaye' and its Dena'ina name is Ch'atanhtnu Dghelaya.